It's just giving you the information that the stitch pattern is a multiple for 2 sts - those are the sts that will be repeated - plust 1 more. So basically any odd number over 3 is correct, no matter what the size.

Well if the pattern is a multiple of 2 stitches + 1 then that applies to all sizes. There is a pattern stitch that requires 2sts which are repeated a ceertain number of times with one extra st before or after the repeat. So in your case it's 2sts times 12 repeats plus one = 25sts.